During the 47-year period 1935 through 1981, 30 cases of malignant bone and joint tumors (in 20 male and 10 female patients) were identified among Olmsted County, Minnesota, residents. The incidence rates per 100,000 population, age-adjusted to the 1970 US total white population, were 1.0 overall, 1.4 for male subjects, and 0.7 for female subjects. Mortality rates, likewise age-adjusted, were 0.7 overall and 1.1 and 0.3 for male and female subjects, respectively. These rates are similar to those from tumor registries, a finding that suggests that reporting of these tumors is relatively complete. The similarity of the incidence and the mortality rates is consistent with the high case-fatality rate. A comparison of the Olmsted County cases with Mayo Clinic referral cases provides some evidence for referral bias, as the referral patients were significantly younger and had significantly more high-grade tumors.